Slugging is a TikTok trend with roots in K-beauty that has divided the skincare world into two camps. Some swear by petroleum jelly as the final step in their skincare routine, while others warn of clogged pores. We check what dermatology says — and when occlusion makes sense, and when it’s better to skip it.
What exactly is slugging?
Slugging is the last step of an evening skincare routine, involving applying a thin layer of an occlusive product — most often petroleum jelly — over the entire face. The name comes from the English word "slug," because in the morning your face shines like a slug after rain.
The trend exploded on TikTok in 2021, but it actually has roots in Korean skincare (K-beauty), where occlusion has been used for decades. Korean grandmothers were applying petroleum jelly to their faces long before any influencer recorded a video about it. In dermatology, occlusion is a well-known technique — used, for example, after laser treatments or deep peels to protect the skin during the regeneration phase.
Mechanism: why does it even work?
To understand slugging, it’s worth knowing one acronym: TEWL — Transepidermal Water Loss. This is the process in which water from the deeper layers of the skin evaporates through the epidermis into the environment. It is natural and unavoidable, but it intensifies when the skin barrier is damaged — by dry air, wind, excessive exfoliation, or after treatments.
Petroleum jelly creates a physical barrier on the skin's surface that drastically reduces TEWL. Dermatological studies have shown that it can reduce transepidermal water loss by as much as 98%. In comparison: mineral oil reduces TEWL by about 20–30%, and lanolin by a similar amount.
Important: petroleum jelly does not hydrate the skin in the classical sense — it does not provide water. It seals in the water that is already there. It acts like plastic wrap on a bowl of salad — it doesn’t add flavor, but prevents drying out.
The big myth: petroleum jelly clogs pores
"But petroleum jelly is comedogenic!" — this argument comes back like a boomerang in every discussion about slugging. It’s time to dismantle it.
Pharmaceutical-grade petroleum jelly has a comedogenicity index of 0–1 on a scale of 0–5. In comparison: coconut oil, which many people use on their face without hesitation, has an index of 4. Cocoa butter — 4. The molecules of petroleum jelly are too large to penetrate the openings of sebaceous glands — it literally "sits" on the surface like a blanket, not penetrating deeply.
A study published in the Journal of Cosmetic Dermatology in 2016 confirmed that regular use of petroleum jelly on the face does not increase the incidence of blackheads in people with normal and dry skin.
Petroleum jelly does not clog pores by itself — but it can trap everything you apply underneath it. If makeup, sebum, or bacteria get under the petroleum jelly — occlusion will seal them in along with the water. That’s why slugging works ONLY on perfectly cleansed skin.
When slugging is a game changer
Slugging can really work in specific situations:
- Dry and dehydrated skin — if your skin is constantly flaking, feels tight, and cream absorbs in seconds only to feel dry again, occlusion may be the missing element. You hydrate, hydrate, but the water escapes — petroleum jelly stops the escape.
- After retinol — retinization (dryness, peeling, burning) is a classic case of a damaged barrier. Many dermatologists recommend the so-called "retinol sandwich": moisturizer → retinol → petroleum jelly. Occlusion soothes irritation and allows retinol to work.
- Winter and heating — the air in heated apartments drops to 20–30% humidity, and the skin loses water at an alarming rate. Slugging in winter can be a lifesaver for any skin suffering during the heating season.
- After in-office treatments — peels, microneedling, laser treatments — after each of these, the skin needs an occlusive protection during the recovery phase.
- Lips and eye area — even if you don’t want to apply it all over your face, slugging on the lips and under the eyes can work for any skin type.
When slugging is a bad idea
Slugging is not for everyone and not in every situation:
- Oily and acne-prone skin — if your skin produces excess sebum, adding occlusion creates anaerobic, warm, and humid conditions that Cutibacterium acnes particularly loves. The result can be new inflammatory lesions and worsening acne.
- Rosacea and sensitive skin — occlusion creates a greenhouse effect, raising the skin temperature under the layer of petroleum jelly. For skin with rosacea, which reacts to heat with vasodilation and redness, this is a common factor that exacerbates symptoms.
- Active inflammatory conditions — eczema, atopic dermatitis in the acute phase, fungal infections — occlusion traps pathogens and inflammatory mediators under the barrier.
- Hot, humid climates — in August heat, when humidity reaches 70%, the skin does not lose as much water, and additional occlusion can lead to overheating and sweating.
Alternatives: slugging 2.0
If the idea of occlusion tempts you, but pure petroleum jelly isn’t your thing — you have options:
- Squalane — a lightweight, biomimetic oil identical to natural squalene in the skin. Gentle but effective occlusion. Comedogenicity index: 1. A good solution for combination skin.
- CeraVe Healing Ointment — a product with petrolatum, ceramides, and hyaluronic acid. Less intense finish than pure petroleum jelly.
- Shea butter — a natural occlusive with vitamins A and E. Works well for the body and lips. On the face — rather for dry skin types.
- Petroleum jelly + niacinamide — a clever hack: add a drop of niacinamide serum to petroleum jelly. Niacinamide strengthens the barrier and regulates sebum production, alleviating potential side effects of occlusion.
“Polish slugging" — our approach
Instead of mindlessly copying TikTok trends, we propose a rational approach tailored to our climate and lifestyle:
- Thorough cleansing — double cleansing (oil + gel) in the evening. No compromises.
- Ceramide serum — rebuilding the barrier from within. Ceramides are the natural "cement" between skin cells.
- A thin layer of occlusion — petroleum jelly, squalane, or healing ointment. Really thin — the amount the size of a pea for the entire face.
- Frequency: 1–2 times a week — not every day. As an SOS when the skin cries for help, not as a daily ritual.
- Only fall–winter — in the Polish climate, slugging makes the most sense from October to March.
What do dermatologists say?
Most dermatologists view slugging neutrally-positive. Dr. Ranella Hirsch, a dermatologist from Boston, sums it up well: "Petroleum jelly is one of the most studied ingredients in dermatology. The problem is not the product — the problem is in improperly matching it to skin type."
Polish dermatologists add important context: the temperate climate means that our skin needs occlusion mainly in winter. In summer — rarely.
Petroleum jelly vs. in-office treatments: can they be compared?
Petroleum jelly is a great occlusive product. But occlusion is just one moisturizing mechanism — and the simplest one. Professional moisturizing works on many levels simultaneously:
- Humectants (hyaluronic acid, glycerin) — attract water
- Emollients (ceramides, lipids) — smooth and seal the barrier
- Occlusion (petroleum jelly, silicones) — lock in water
- Active moisturizing (mesotherapy, sonophoresis) — deliver ingredients deep into the skin
Petroleum jelly covers the third point. A professional treatment can work on all four levels simultaneously. It’s like comparing aspirin to comprehensive therapy — aspirin can help, but it doesn’t treat the cause.
Slugging is a clever, inexpensive, and well-researched trick — but it cannot replace professional care. If you want to know if occlusion is right for your skin and what kind of moisturizing you really need — we invite you for a consultation at J'ADORE INSTYTUT. Our specialists will assess the condition of your skin barrier and propose a moisturizing strategy tailored to you.
